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An Italian geophysicist who attended a meeting at the center of a trial alleging scientific negligence in connection with the deadly 2009 L'Aquila earthquake told a court that he had serious doubts about the scientific basis of some of the statements made during the meeting.

Christian Del Pinto testified yesterday during the trial of seven scientists and technicians who face manslaughter charges for allegedly failing to properly assess seismic risks ahead of the earthquake that devastated the central Italian town of L'Aquila on 6 April 2009. Having previously heard from relatives and friends of the deceased, prosecutors took evidence from those present at the experts' fateful meeting held a week before the magnitude-6.3 quake, which killed 308 people.

The seven were called upon as full or acting members of Italy's national commission for the forecast and prevention of major risks to analyze the threat posed by a "swarm" of hundreds of small tremors that had been taking place in the Abruzzo region around L'Aquila since the end of 2008. The prosecution does not contend that the experts should have been able to predict when, where, and with what magnitude a major quake would have occurred. Rather, it argues that they carried out an "approximate, generic, and ineffective" risk evaluation that provided townspeople with a false sense of security and led many to stay indoors the night before the quake rather than leave their homes.

The trial, which started on 20 September, centers on the commission's meeting held in L'Aquila on 31 March 2009, the day after a magnitude-4.1 tremor shook the town. Del Pinto is employed by the civil protection department in the neighboring region of Molise, but he was attending the meeting out of personal interest. Del Pinto told prosecutors yesterday that he was troubled by the group's description of the ongoing swarm of tremors as a "normal phenomenon," adding that extra vigilance is needed whenever a swarm is registered. "For me, a swarm is never normal," he said, "even if the great majority of swarms, thank God, don't result in a stronger event."

Del Pinto also took issue with another statement he claims was made by a commission member, namely, that there is little chance of a sudden increase in the magnitude of tremors within a swarm. But that was exactly what had happened on 30 March, he said, given that the strongest event within the swarm registered up to that point was of magnitude 2.9. As such, he argued, it was wrong to rule out further sudden rises in magnitude.

The prosecution's argument that the experts had underplayed the possible occurrence of a major quake was bolstered by testimony from Daniela Stati, the former civil protection officer for Abruzzo, who took an active role in the March 31 meeting. Stati confirmed what she had previously told prosecutors in 2010, that one of the indicted said during the meeting that the continuing tremors represented a "favorable signal" because there was a continuous discharge of energy that made stronger tremors less likely. (In fact, scientific evidence suggests that groups of small earthquakes tend instead to increase the chances of a major earthquake nearby, even though the absolute probability of such a quake remains low.) Stati said that nobody within the commission objected to the upbeat assessment. She also underlined that the "reassuring message" given to the press by her, L'Aquila Mayor Massimo Cialente, and two of the indicted, Franco Barberi and Bernardo De Bernardinis, was based on comments made at the meeting.

The testimony from Cialente, the day's final witness, also generated controversy. In part this was because the defense declined to ask him questions about what took place during the meeting. Cialente, who is in charge of civil protection at the local level, told prosecutors that he didn't arrive until the meeting was almost over and that he hadn't realized the commission was even holding the meeting. He told Judge Marco Billi that his perception of the seismic risk had not been altered by the deliberations of the commission, and he also noted that, in any case, he had made sure that local officials "knew what to do" if and when an earthquake struck. Challenged by civil prosecutor Fabio Alessandroni to describe what emergency plans he had actually drawn up, Cialente replied that the plans had been created by his predecessor.

The trial will resume on 12 January. With almost 300 witnesses scheduled to testify, the judge is not expected to reach a verdict before the fall of 2012.